1. Field of the Invention
This invention relates to semi-transparent artifacts or ‘blotches’ that are introduced onto film or a digital image by contaminants in the camera's optical path, and more particular to an efficient method of removing these blotches.
2. Description of the Related Art
Digital and film cameras have a series of lenses 10 that capture light 12 from a scene for a motion picture and project it onto a image plane 13 where it is captured by a recording mechanism 14 such as a digital sensor or film. When the lenses 10 or other elements in the optical path such as dust cover 16 are not properly cleaned, contaminants 18 such as small water spots, thumb prints or small pieces of dirt can accumulate inside the lenses or close to the focal plane 20 of the camera. The miniscule contaminant, shown here on dust cover 16, is projected onto a much larger area in the image plane 13 where it forms an artifact 22 that is captured by the digital sensor or on the film. These blotches are very noticeable when watching a sequence of images.
If the problem is discovered during shooting, the lenses can be cleaned and the scenes reshot. However, the more typical situation is that the problem is not discovered until post-production. At this point, there are three options to handle artifacts. The first option is to do nothing and live with the artifacts, which given the production standards of 1st run feature films and the transition to digital cinema is an unattractive option. The second option is to reshoot the affected scenes, which can be cost and time prohibitive. The third option is to manually retouch the affected digital images in post-production. Because the content of the imagery is generally changing throughout the scene, to ensure quality each and every image is typically individually retouched. This can take considerable tedious manual labor as the number of contaminated images in a scene can number into the several thousand.